'Extreme weather is not increasing to any significant degree'

The concentrations of three main greenhouse gases blamed for global warming were at record levels last year and will linger for decades, according to a recent Reuters article that cited the United Nations’ weather agency.

But three experts contacted by Michigan Capitol Confidential are critical of the news story.

John Christy is a professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville. He also served as Alabama's state climatologist.

Christy questions a paragraph in the story that reads: “The report adds to a number of warnings that time is running out to act on climate change and prevent worsening extreme weather as the Earth's temperature rises.”

“Extreme weather is not increasing to any significant degree,” Christy wrote in an email. “The latest IPCC (Intergovernmental Panel on Climate Change) draft even says so.”

Christy said the concentration of carbon dioxide was several times higher when plant life evolved than it is now. “So these are far from being ‘record amounts’ when Earth’s history is considered.”

Increased carbon dioxide is also a sign of an improving world related to the standard of living “for those who struggle the most,” Christy said.

David Legates is a professor of geography and the former director of the Center for Climatic Research at the University of Delaware. He also served as the Delaware state climatologist. He said the main greenhouse gas is not carbon dioxide but rather water vapor, which can’t be regulated.

“Water vapor accounts for about (five-sixths) of the warming attributable to all greenhouse gases,” Legates said in an email.

Legates said greenhouse gases often increase the concentrations of carbon dioxide in the air and enhance growth and make plants more efficient with their water use.

“Despite what we are often told by the media, climate is more variable during colder times than warmer periods and storminess actually is less (both for tropical activity and mid-latitude weather systems). Thus, increased CO2 has significant benefits both for plants and our climate,” Legates said. “ … despite dramatically rising levels of CO2, mean global temperature has remained relatively constant over the last 10 to 15 years. That means that something at least as important as CO2 has been affecting our climate and that greenhouse gases are NOT the single most important driver in climate change. Note too that climate has always changed and it always will -- any policy that attempts to 'stabilize' global temperatures is destined to fail since it purports to stop nature!”

William Happer is a professor of physics at Princeton University and is a former director of energy research at the U.S. Department of Energy.

Happer wrote in a study that before the industrial revolution, the concentration of carbon dioxide in the atmosphere was about 270 parts per million (ppm). He said currently it is about 390 ppm. Happer said geological evidence indicates that about 50 million years ago, carbon dioxide levels were several thousand ppm, “and life flourished abundantly.”

Happer wrote in an email that carbon dioxide levels are increasing at a rate of at 2 ppm per year, and so it would take 600 years at that rate to add 1,200 ppm.

“And over most of the geological history of the earth, CO2 levels have been higher than 1,600 ppm. Plants would love it, and the rest of the world biosphere would also benefit.”